As telecommunication bandwidths increase, there is a strong demand for low power consumption, low cost, high bandwidth transmitters and receivers. To increase bandwidths of optical transmissions between two points, wavelength division multiplexing (WDM) can be used in which information is carried on different channels, e.g., N channels, each at a unique wavelength. Adjacent points can be, for example, many kilometers away from each other. The channels can be arranged on a wavelength grid, e.g., with uniform spacing in wavelength or frequency, such that the spectral content in each channel does not interfere with adjacent channels. Also, an increase in bandwidth can be achieved using modulation at higher data rates. Generally, current technology involves WDM of 4 to 100 channels and data rates of 2.5 gigabits/second (G), 10 G, 25 G or 40 G, although it is expected that these values of channel number and modulation rates will evolve over time.
Nodes along a communication network can involve transmitters and or receivers to interface appropriately with the optical communication signals. Optical fibers with multiplexed optical signals generally are used to connect remote points on the network. If the optical channels are on a wavelength grid or frequency grid, the synchronization of the wavelengths can be expensive and can dissipate considerable power, e.g. to maintain temperature control. Precise control of device production and operating conditions is typically needed with communication systems involving narrowly spaced wavelength channels to align channel wavelengths with the narrow, passbands of multiplexors/demultiplexors.